High-temperature lubricating greases



July 25, 1950 A. J. MoRwAY ET AL HIGH-TEMPERATURE LUBRICATING GREASES oNOE Gm*n 0 2. o2 om 99 2 Sheets-Sheet l O vf) IN T-)QESSUQE (La-5J ma)Filed Nov. 17, 1948 July 25, 1950 A. J. MoRwAY Er A1.

HIGH-TEMPERATURE LUBRICATING GREAsEs 26mm, Om@l Om, 00N ON@ Om@ 00N. OiwOm O5 Om* Ow* 2 Sheets-Sheet Filed Nov 17. 1948 .m.%\\0\ O Om Ow. Og

OENT.

PRESSURE. 0.155./ IN2) John QJ. Kolfen Pgenea July 2s, 195o UNITEDnien-TEMPERATURE LUnalcA'rmG GaEAsEs v mola J. norway. clark, and JohnJ. neuenbach, Somerville, N. J., assia'nors to Standard Oil DevelopmentCompany, a corporation ot Delaware Application November 17, 1948, SerialNo. 60,815

22 claims.

The present invention relates to the production of high temperaturelubricating grease compositions, and the like, and particularly to theproduction of a new type of lubricating grease which retains hightemperature structure stability over extended periods of-time. Theinvention relates further to a process for preparing such greases from acombination of high molecular weight metal soaps and low molecularweight salts of certain organic acids, especially certain heterocycliccompounds. It relates particularly to a process for incorporating themetal salts of such compounds, especially of carboxylic acids, in situin grease compositions.

The invention further comprises a process for preparing the desiredsalts of such carboxylic acids, and the like, in lubricating greases bysubjecting certain typesof aldehydes .to treatment with alkalinematerials, thereby causing them to undergo the well-known Cannizzaroreaction to make the carboxylic acids available.

It has previously been suggested in the prior art, that for somepurposes it is advantageous to combine certain metal salts of relativelylow molecular Weight with the metal soaps ordinarily employed asthickeners for lubricating grease compositions. There appear to be anumber of opinions as to the eifect of such combination on ingredients,but various investigators have found that the addition of metal salts ofrelatively low molecular weight organic acids has some utility in greasecompositions. Some have suggested that the addition of the low molecularweight acid compounds to the relatively high molecular weight soapsresults in the formation of a complex of salt and soap, with superiorgrease thickening eiect and of improved stability, for example, atelevated temperatures. On the other hand, it may be that the provisionof a lower organic salt to be used with the soap tends to offset anormal tendency of some of the soaps of certain of the higher fattyacids, especially the more unsaturated acids, to break down into lowermolecular weight substances. It is probable that the equilibriumexisting in the soaps is shifted somewhat by the addition of these lowermolecular weight materials.

Whatever may be the phenomena involved, the addition of salts, and thelike, of relatively low molecular weight compounds appears to beadvantageous especially in alkali and alkaline earth metal base greases.These materials, in many cases at least, improve physical structure ofgreases and are particularly useful in stabilizing them structurally atelevated temperatures be- 2. cause the ingredients themselves are morestable. Greases which include them appear to be quite susceptible, also,to further stabilization by conventional oxidation inhibitors.

Although various low molecular weight compounds have been proposedrecently, such as the salts of acetic and propionic acids and certain ofthe lower unsaturated acids, such as acrylic and crotonic acid, and thelike, as being particularly useful as grease modiers, these acids arenot always suitable and the more desirable of them are rather expensive.Hence, one object of the present invention is to replace such lowmolecular weight acids with a material which is abundantly available andrelatively inexpensive, as well as being particularly eiective as amodifying agen A further and important object of the present inventionis to take advantage of the well-known principles of the Cannizzaroreaction to convert inexpensive aldehydes directly into low molecularweight compounds which are highly useful for modifying soap-thickenedlubricating greases, thus making unnecessary the use of costly acids ortheir salts.

Another object of this invention is to produce lubricating greaseshaving the` usual desired grease structure forming ingredients, i. e.,metal soaps of higher fatty acids, along with metal salts of lowmolecular weight unsaturated compounds, in a simple, direct andinexpensive manner.

An additional object is to improve theCannizzaro reaction process, asapplied to furfural and like aldehydes, by controlling the reaction,causing it to take place under controlled conditions in the presence ofa liquid hydrocarbon such as mineral oil.

Still another object is to utilize inexpensive raw materials, such aseffluents from hydrocarbon treating processes as well as the by-productswhich may be formed in the Cannizzaro reaction either by incorporatingthem with suitable modication, into the nished grease composition asuseful ingredients thereof. Other and further objects will become morefully apparent as this description proceeds.

According to the present invention, the salts of certain low molecularweight acids, which may be derived from corresponding aldehydes,preferably the aldehydes of cyclic compounds, and particularlyheterocyclic carboxylic acids such as furoic acid, are highly useful asingredients of lubricating greases and are very easily and inexinafter,it will be understood that the related cyclic and heterocycliccompounds, including the thio compounds, are contemplated as beinguseful in this invention.

According to the Cannizzaro reaction princlple, an aldehyde which has nohydrogen dlrectly attached to the alpha carbon atom may be treated withan alkaline material such as sodium hydroxide, for example, to oxidizeone molecule of aldehyde to an acid radical at the expense of anadjacent molecule which ls converted to the alcohol. Thus, an aldehydeof the general formula RMC-CHO, where R may be any organic substituent,is treated with strongly a1- kaiine material, resulting in convertinghalt oi' the aldehyde into the corresponding alcohol and the other halfinto the metal salt of the corresponding carboxylic acid. ThisCannizzaro reaction is obviously applicable to formaldehyde, as may beseen in any standard work on organic chemistry, as well as to the higheraldehydes having no hydrogen on the alpha carbon atom,

y where an alpha carbon atom is present, Hence,

fural, is abundantly available and quite inexpensive, being a by-productof certain of the cereal grain industries such as as the oatmealindustry.

It is recoverable in large quantities by the sulfuric acid treatment ofmaterials containing pentosans, such as corn cobs, oat hulls, bran, andthe like. The Cannizzaro reaction, as applied to furfural, proceeds asfollows:

The resulting products are respectively the sodium salt of furoic acid(pyromucic acid) and furfuryl alcohol.

One aspect of the present invention is the superior results obtained byconducting the Cannizzaro reaction in the presence of a control diluentsuch as a hydrocarbon oil. Where a lubricating grease is to be produced,the diluent may be the same oil as is to serve as the liquid phase ofthe lubricant. This is not always necessary however. The Cannizzaroreaction taking place under the control afforded by an oil solutionappears to have particular merit per se, aside from the final use towhich the reaction products are put. A light oil or a volatilehydrocarbon may be used. to be evaporated later if the reactionproducts, especially the salt, is the desired product. If a grease is tobe prepared, as hereinafter described, a heavier oil, or an oil of anydesired grade, may be compounded with th salt or other products ofreaction.

The Cannizzaro reaction releases alcohol, as previously noted. Where thetemperature is permitted to rise appreciably, the alcohol derived fromfurfural under the Cannizzaro reaction may be polymerlzed. The resultingpolymers, whose molecular weight, viscosity, and other properties varywith the temperature and with other reaction conditions (pressures,presence of catalytic materials. and the like) may be of value forseveral purposes. The inclusion of at least a small amount of suchpolymers in the grease appears to be advantageous in at least someinstances and is a further feature of the present invention. Thecombination of the metal furoate and the polymerlzed alcohol, along withthe lubricating oil and soap, forms a grease of superior properties.

'I'he sodium salt and the alcohol may be produced during the ordinarygrease-forming reaction by adding the alkaline material in suitablequantities to cause the Cannizzaro reaction to proceed. At the same timeor preferably subsequently, there may be formed the soap by saponifyingconventional higher fatty acids with a suitable base. Preferably, thealdehyde and the l alkali are reacted first in the presence of some partof the lubricating oil. The use of some of the oil, which is chemicallyinert, helps to reduce the violence of the reaction. which isexothermic, and thereby control the temperature. The fatty acids to besaponied are added later, together with additional alkali, if required,The remainder of the lubricating oil, which forms the liquid element ofthe grease, preferably is added last.

The use of salts of relatively low molecular weight organic acids, suchas furoic acid, is not to be confused with the use of related estershaving entirely different purposes. Thus, in the Zimmer and Morway U. S.Patent No. 2,113,754, granted April 12, 1938, there is disclosed the useof certain esters. including some furoic acid esters, as oiliness agentsin various materials including both lubricating oli and lubricatinggreases. The estersrused. however, are entirely different from the saltsemployed in the present instance, and their function is not related inany way to the function of the furoic acid salts and their equivalents.

In the present case, these salts are added to improve the temperaturestability of the grease and to amplify the thickening effect of thesoaps. The present process is particularly meritorious because theingredients may all be combined in a single kettle and the same alkalinematerial which is used to promote the Cannizzaro reaction may be andpreferably is used to saponify the higher fatty acids. Thus, both thesoap and the salt are formed in situ in the grease. The undesiredreaction products such as water and alcohol, or at least part thereof,and other volatile constituents which may be present, are readilyremoved by evaporation.

The relative proportions of the high molecular weight soaps and the lowmolecular weight salts, prepared from aldehydes as indicated above, maybe varied rather widely. Broadly, molecular proportions of about 1 to 4parts of soap may be used with about l to 4 parts of the salt. Ingeneral, however, it is preferable that the molecular proportions bemore nearly equal and molar proportions of about l to 1 or 1 to 2 areusually preferred. The total quantity of these ingredients to be used ina given grease composition will vary depending upon the type of greasedesired. For

a very still grease. the proportions of total thickener may approach 50%total whereas for a soit grease the total of soaps and salts may beaslow as about 5%, based on the weight of the total composition. Ingeneral. the Urease will consist i a lubricating oil containing 3 to 30%by weight of the metal soap of C1: to Cn fatty acids along with 2 to 20%of the metal salt of the low molecular-weight heterocyclic carboxylicacid. Narrower limits otto to 25% soap and 3 to 15% ofk salt are usuallyadequate.

With regard to the relative proportions of high molecular weightsoapsand low molecular weight salts, it appears -that a fairly high molarratio of salt to soap is desirable where the soap con-'- tent of thefinished grease is or more'by weight; When the soap content is less. thesalt content should be reduced more than proportionally. Thus, whenthese greases were prepared with relativelylarge concentrations of soap(15% or more) the optimum ratio to give the best grease structure andperformance was a ratio of 10 parts furfural to 15 parts hydrogenatedfish oil acids or 2:3 by weight. These data are shown below:

EXAMRLEI Furfural (forms sodium furoate by Cannimaro reaction) v(58%conversion) Hydrogenated sh oil acidsx Sodium hydroxide Dial 55Structure o! creases prepared with varying ratios of furfural toHydrofol Acids 54 l charged 'Ihe above data has shown that whenvquantities of soap are employed to thicken the greases (total soapabove 15%), the greases containing structure at elevated temperatures ofthe greases having an acid ratio of 1:2 is less pronounced. The tendencyof the greases to become heavier (increase in apparent viscosity) atelevated temperatures is desirable since the greases containing a 2:3ratio thin out too much and may not remain in the bearings. See FigureII.

Wheel bearing lubrication tests employing the CRC laboratory WheelBearing tester also show the greases prepared from 5.0% furfural and'7.5% fatty acids, such as the'hydrogenated fish oil acids mentionedabove, become soft and tend to flow out of the wheel hub, while greasesprepared from 4.0% furfural and 8.0% of the same fatty acids remain inthe hub \and show only minor separations of oil. These data are shownbelow:

PewCelli)t weiight R ti (W te) M l R ti a o g o a o e Fammi: Fume Aci:Grease Structure Wheel bearing tests at 220 F.

H d 'fi Hyd'sfdds yiwl y. roo c s 5 Fuffa@ Ac1ds54 3PeroentWeightCharged Ratio Weight,

Results o'iIWheel Bearing 1o 5 2:1 3:1 None. Hydmfoi y '0 0 em f 1o 1o1:1 3:2 Poor-grainy. Fuffuml Acids 54 Acids 54 10 l5 2:3 1:1 Excellent.

7.5 l5 1:2 1:1.4 Good-rubbery at ele- 40 5 7.5 2:3 Flows from wheelhub.

vated temp- 4 8.0 1:2 Remains in wheel hub peratures. trace of oilseparation.

lSaturated high molecular weight aliphatic acids of C average chain181mm Greases with higher soap content than those shown above giveexcellent results with no flow The above data show that a 1:1 mol ratioof furoic acid to Hydrofol Acids 54 gives the bcst grease structure.Data below will show performance characteristics of these greases.

Lowering of the -soap content of the greases to below 15.0% (total soap)indicates that a more desirable structure with better performance can beobtained by increasing the concentration of the high molecular weightsoap to give ratios of 1:1.4 or even 1:1.6 or even 1:2 mol'ratios ofiuroic acid to Hydrofol Acids 54 or a charging ratio of 2 parts fattyacids to l part furfural.

Furfural greases containing less than 15% total l 58% conversion ofiuriural chargedto iuroic acid by Cannizzaro reaction.

from the hub whether prepared with 2:3 or 1:2 molar ratio of furfural tofatty acid.

Although the sodium soaps and salts are specifically preferred for manypurposes, there lare many instances where other metals are moredesirable. Lithium base greases may be prepared by the same method asmay also greases of calcium, strontium or barium base. Mixed basegreases may also be prepared.

For most purposes, the mineral base lubricating oils are preferred,ranging from viscosites from as low as about S. S. U. at 100 F., orabout 35 S. U. S. at 210 F., up to as high as about 1.000 S.,U. S. at210 F. The invention is not limited, however, to the use of mineral baseoils since various synthetic oils may also be used as part or all of theliquid phase of the grease, as is well-known in the art of greasemaking. Certain synthetic esters, especially the dibasic acid esterslike di-Z-ethylhexyl sebacate and related materials are preferred forcertain purposes where unusual temperature conditions are encountered,particularly in unusually low temperatures. The grease-thickeningingredients of the present invention are just as useful in synthetic ormixed oil greases as in those based entirely on mineral lubricatingoils.

The invention will be more fully understood by reference tol thefollowing further specific examples:

A series of soda base greases were prepared using respectively 10%,7.5%, and 5%, by weight, based on the total ingredients,A of Iurfural,the other ingredients being adjusted proportionately. 'Iihese greaseswere graded as heavy, medium, and light, respectively. The compositionsthus prepared and some oi' the inspection data are indicated in Table I.

TABLE I Furfuraldehyde areasea Ingredients Per Cent Weight Medi- GradeHeavy um Light Furlural 10. 7. 6 6.0 Sodium Hydroxida-. Cannizzaro 3.22.4 1.6 Mineral Oil 1-..---." 10.0 10.0 10.0 Hydroganated fish o acids("Hydrolol 54 16.0 ll. 3 7. 5 Sodium Hydroxide 2.3 1. 6 l. 2 Phenyl alhanaphthylamine- 1. 0 1.0 1.0 Mineral 0 l 68.6 66 2 73. 7 Free Alkalinity,cent NaOH- 0. 4 0.2 0. 2 Worked Penetrat on, mm./ 200 260 332Penetration after 75,000 Strokes, fine hole plate, mm./l0 230 265 290Dropping Point, F 500+ 600+ 600+ Water Washing, per cent Loss 126 F.Water 6.0 0.0 0.0 Oil Separation (60 Hours at 210 F.), per

eent..- 0.0 1.5 3.5 10,000 R. P.M. Spindle, 300 F.,Hours.... 1,178 600m0 Norma Hoilman Glass, Hours for 6 p. s. i.

drop in oxygen pressure 500+ 500+ 600+ mliiht color low pour naphthenicoil of 55 S. S. U. vis. at 210 Fm When the grease is heated to hightemperatures o1' the order of about 500 F., the alcohol which isreleased in the Cannizzaro reaction is evaporated to the atmospherealong with water and the more volatile constituents of the mineral oilunless steps are taken to salvage these materials. It is usuallydesirable to save the alcohol,

and this may be done by condensing the water and alcohol mixture. Thealcohol solution or part thereof may be added back to the grease aftercooling, if desired, to serve as an oiliness agent. It may be used alsoin other types of grease, being a good mutual solvent or solubilizer forlow molecular weight materials, as where other low molecular weightsalts are used such as sodium acetate, and the like. The alcohol whichis water soluble, forms therewith an azeotropic mixture and must bespecially treated to separate the water. Ordinarily, it is not desirableto utilize all the alcohol in the grease and in many cases it ispreferable to remove it entirely. Furfuryl alcohol is highly combustibleand care should be taken in its withdrawal. The polymerized furfurylalcohol, as previously noted, is a good additive for greases. 'I'healcohol and its polymers serve as plasticizers which are usuallydesirable. These may be replaced wholly or in part, however. with otherplasticizers which are known in the art.

EXAMPLE III Employing the Cannizzaro reaction, the following ingredientswere used in the weight percentages indicated to prepare a verysatisfactory 1ubricating grease:

10% Furiuraldehyde 5.4% Sodium hydroxide 15.0% Hydrogenated fish oilacids as in Example 68.6% Mineral oil as in Example II 1.0% Phenyl alphanaphthylamlpe 'me furruim and equal quantity of mineral oil was chargedto a cold grease kettle and agitation started. About 60% of the sodiumhydroxide was next added in the form of a 33.3% aqueous solution. Noattempt was made to control the temperature of reaction. and thetemperature rose to about 175 F. Stirring was continued Ifor about 1% to2 hours and then the fatty acida and about 1,/3 of the mineral oil werecharged to the kettle, heat being applied to raise the temperature toabout `160 F. since the reaction product had cooled somewhat during thestirring interval. The remainder of the sodium hydroxide was then addedin a 33% aqueous solution and the temperature thereafter was raised to350 F. The remainder oi' the mineral oil was next added in smallincrements. Thereafter, the temperature was raised to 450 F. toevaporate all the water and other volatile constituents. Theseconstituents were withdrawn. After heating was discontinued, the greasewas stirred while cooling down to about 250 F. At this temperature,stirring was discontinued and the grease was allowed to cool in thekettle. When cold, it was paddled in the kettle to a smooth oilyappearance and iinally filtered into containers. See the heavy grease ofTable I for the properties of this composition.

In the examples given above, sodium hydroxide was used as the alkalineagent. However, the Cannizzaro reaction will proceed with other alkalinebases such as lithium, potassium. strontium, barium, calcium, aluminumand mixtures thereof. It is not necessary, either, that the furoate andthe soap be formed oi the same metal base. The strong bases, such assodium hydroxide, are usually preferred, however.

While the saturated acids oi.' 12 to 22 carbon atoms are particularlysuitable because of their stability for forming the soaps, theunsaturated or hydroxy acids of similar molecular weight may also beused. as will be obvious to those skilled in the art.

As suggested above, various synthetic oils may be used in lieu ofmineral oil. Thus. furtural may be reacted as above, with sodiumhydroxide or other metal hydroxides, to form a metal furoate, and themetal furoate, in combination with the soap of a high molecular weightacid, may be dispersed in ester oils such as di-Z-ethylhexyl sebacate,or they may be used in glycolate, silicone, iluorinated hydrocarbons. orvegetable oils such as castor oil to form a grease structure. The estertype oils may include those wherein oxoalcohols are employed to esterifydibasic acids,

f and the like. The salts and soaps preferably are not prepared in situin the ester oils because .the ester type lubricants tend to hydrolyzeduring neutralization of the acids. If it is desired to slow down theCannizzaro reaction, mineral base oil may be used as a diluent, usingesters as the remainder of the lubricating oil, so long as such estersor synthetic oils are readily miscible with mineral base oil.

The salts of furoic acid may also be combined with detergent materialssuch as the sodium or other metal sulfonates. For example, aromaticsulfonates such as toluene-Cu-alkylate sulfonates are particularlyuseful.

Furi'ural and furoic acid are closely related to the aromatic aldehydesand acids. Hence aromatic aldehydes such as benzaldehyde may be employedin lieu of furfural. In fact, any aldehyde of appropriate molecularweight. i. e., lower 1| than the Cia and higher aliphatic carboxylicacida used in making the soaps, may be employed which undergoes theCannizzaro reaction such as glyoxal, formaldehyde, substituted aromaticaldehydes, such as tolualdehyde, and the like, though the cyclicmaterials appear to be preferable in greases. Especially useful arethose aldehydes in which the alpha carbon atom does not have anyhydrogen atom attached to it. Substituted aromatic aldehydes in whichgroups other than alkyl are present on the aromatic ring also appear tobe suitable. These may include chloro and nitro derivatives which mayhave some load-carrying properties.

In addition to conventional aldehydes, aldehydes which contain sulfurmay be employed as suggested above. These include the various types ofaldehydes enumerated above, wherein sulfur is substituted for the oxygenof the conventional aldehyde. Also, aldehydes may be employed whichcontain sulfur elsewhere in the molecule. An example of the former isthe thiophene derivative By thus incorporating sulfur into the molecule,it is possible to increase the load-carrying properties of thelubricating grease. The hydrogenated derivatives appear also to beapplicable, provided the hydrogen atom on the carbon adjacent to thecarbonyl group is replaced either with an alkyl group or with some otherinert group. Obviously, mixtures of the various aldehydes referred to,may be treated together in the Cannizzaro reaction to produce mixedsalts for use as lubricating oil thickeners in grease manufacture.

While the hydroxides, and particularly the hydroxides of alkali andalkaline earth metals, are preferred for neutralizing the acids or forcarrying out the Cannizzaro reaction, other strongly alkaline compoundsmay be used. These include the oxides, carbonates, phenolates,alcoholates and certain sulildes.

In many cases, it is not necessary to catalyze the Cannizzaro reaction,but where the reaction proceeds slowly various peroxides, such asbenzoyl peroxide, cumene hydroperoxide, persulfates, and inorganicperoxides may be used to catalyze the reaction.

As previously indicated, some use may be made of the monomeric or thepolymeric furfuryl alcohols, or both, (or related alcohols) which arereleased in the Cannizzaro reaction, and these materials may also beesteried. The excess alcohol may be combined with an excess of fattyacid to form an ester. Thus, a quantity of the high molecular weightfatty acid may be employed which is in excess of that required forsaponication. Under the usual grease making conditions, which involvecooking at elevated temperatures, of at least 200 or 250 F. and up toabout 500 F., the excess acid esterifies the alcohol which results fromthe Cannizzaro reaction. The resulting ester may be left in the greasewhere it is effective to increase the water repellency of the grease andto improve soap dispersion. The following is a specific example.

EXAMPLE 1V A quantity of parts by weight of furfural, and 10 parts ofmineral lubricating oil, a naphthe-nic oil of 55 S. U. S. viscosity at210 F., are pharged to a grease kettle of the re heated type l0 whilethe kernels com. seamen is started es the kettle begins to heat and 3.18parts of NaOH, on a dry weight basis, are added as a 33t/3% aqueoussolution. This results in the Cannizzaro reaction taking place, asdescribed above.

After the Cannizzaro reaction has been completed, the kettle having beenheated above the boiling point of water for a time period sufficient toremove the water, 15 parts by weight of hydrogenated fish oil acids areadded, together with about 20 parts additional of the mineral oil. Tothis are added 1.4 parts, on a dry weight basis, of NaOH, in aqueoussolution as before. This is somewhat less than the stoichiometricquantity required to saponify the fatty acids, hence free acidsremain,.approximately 0.22 part, calculated as NaOH equivalent.

About 40 parts of mineral oil are next added andthe mixture is furtherheated to about 450 F. Thereupon, about 0.5 part of phenyl alphanaphthylamine are added as oxidatin inhibitor, and the resulting productis pan cooled and ilnally homogenized by stirring in the kettle. Theproduct is a smooth, oily, homogeneous grease.

Tests of the product described, by direct titration, ASTM method, showthe product to be neutral. When tested by back titration after HC1treatment, according to the S. I. L. method, the product showed 0.24%alkalinity, calculated as NaOH.

These data indicate that when the eater, resulting from the excess highmolecular weight acid and furfuryl alcohol, is hydrolyzed, the furfurylalcohol reacts with the strong acid to form an insoluble resin and thereis insuilicient alkali to back titrate, thus indicating an alkalinegrease.

The grease just described was compounded oi' the following ingredients:

0% furfural Cannizzaro reaction 3.18% NaOH 10% mineral oil, 55 B. U. B.viscosity at 210 F 15% hydrogenated ilsh oil acids, Cia-C 1.4% NaOH59.92% mineral oil as above 0.5% phenyl alpha naphthylamine The greaseshowed the following inspection:

Penetration (worked) 77 F., min/10 158 100,000 stroke penetration fivehole plate 225 Dropping point 486 Water washing test (125 F. watertemp.) No Loss High speed spindle test 10,000 R. P. M.-300

F. (hours) 648 It has been observed that greases prepared so as to havesome free acidity are more water resistant, as a rule, than those whichare alkaline, but they are also more corrosive to metal. By usng theabove method of manufacture, however, a grease having the waterresisting properties of acid greases may be prepared that is quite freefrom corrosive tendencies. The following example shows a comparisonbetween standard hydrogenated fish oil acid soap greases of the priorart and that of Example IV.

Humidity cabinet test F.1oo% humidity] Days to Rusting and EtchingHydrofol Acid-Crotonic Acid Grease, Per Cent Free Alkalinity 0.48 asNaOH 4 Hydrnfol Acid-Crotonic Acid Grease, Per Cent Free Acidity 0.45 asoleic acid Grease of Invention In greases where the Cannizzaro reactiondoes not occur during manufacture, other alcohols preferably highmolecular weight alcohols such as oleyl, cetyl, etc., may be added andreacted with the excess acid to form esters in the greases to givegreater plasticizations, ease of dispersion of the soap, waterrepellancy and increased lubrication value.l Hence, the invention is notnecessarily limited to Cannizzaro reaction products, but these appearpreferable at present for reasons of economy.

The quantity of the ester of furfuryl alcohol, or ester of otherappropriate alcohol resulting from the Cannizzaro reaction, may varyfrom as little as about 0.01 to as much as about 5% of the weight of thetotal composition. The preferred range is from about 0.5 to about 3%. Itis understood, of course, that these esters may be omitted altogetherfor many purposes,

As previously noted, it is desirable, though not always essential, toinclude a small amount, e. g., 0.1 to about 1.0% of an oxidationinhibitor such as phenyl alpha naphthylamine in the grease. Otherconventional inhibitors such as phenyl beta naphthylamine may be usedand may be supplemented or replaced by metal deactivators, corrosioninhibitors, and the like. Conventional additives such as extremepressure agents, tackiness agents, and the like, are contemplated asbeing within the scope of the invention.

It has been suggested above that although the major part of thisspecification is directed to a novel improved grease product and a newmethod for its production, the invention involves other aspects ofimproved reactions and reaction products. In particular, the Cannizzaroreaction, although long known in its broad aspects, is markedly improvedby the selection of the vehicle in which it takes place. The use of anoil as a vehicle has particular merit. This oil may be any of numeroustypes, ranging from a very light and highly volatile hydrocarbon to aheavy viscous material. The mineral base oils are preferred, butsubstituted hydrocarbons may be used so long as they are substantiallyinert to the reactants which enter into the process.

By proper choice of the vehicle and by adjusting the proportions ofreactants placed therein, the temperature of the highly exothermicCannizzaro reaction may be accurately controlled. The formation ofpolymers, side reaction products, and the like, may be controlled orsubstantially eliminated. The reaction goes to completion, orsubstantially so, resulting in improved yields of acid salt and alcohol.

The oil, if volatile, may be evaporated to re- 'cover the reactionproducts, or it may be used as an ingredient or additive in greasemaking or other processes. For example, a volatile hydrocarbon may beemployed to control the Cannizzaro reaction, to be evaporated andreplaced by a heavier oil, if a lubricating grease is to be produced.

While sodium hydroxide has been mentioned above as the' usual alkalineagent to be used in the Camiizzaro reaction, any strongly alkaline agentmay be used. For making grease, the agent should also be capable ofsaponifying the higher fatty acids, e. g., C12 to C22 aliphatic acids.The oxides and hydroxides of the alkali metals are generally preferred,but similar compounds of the alkaline earth metals as well as ammoniumbases may also be used.

What is claimed is:

1. The process of preparing a lubricating grease composition for hightemperature use, which comprises combining a cyclic aldehyde capable ofundergoing the Cannizzaro reaction with an alkali to convert part ofsaid aldehyde to a cyclic carboxylic acid salt and part to thecorresponding alcohol, adding a saponiflable fatty material and afurther quantity of alkali to form a soap and adding lubricating oil,said salt and soap being combined in proportions of 1 to 4 molar partsof said salt with 1 to 4 molar parts oi said soap, said combined saltand soap serving to thicken said lubricating oil to a grease.

consistency.

2. Process according to claim 1 wherein said aldehyde is furiural.

3. Process according to claim 1 wherein said alkali is sodium hydroxide.

4. The process of preparing a lubricating grease composition whichcomprises combining 2 to 20 parts by weight of furfural with 1 to 10parts of a metal hydroxide to convert said furfural partly to furfurylalcohol and to form a metal salt of furoic acid, adding 5 to 30 parts offatty acid of 12 to 22 carbon atoms, adding 1 to 10 parts further of ametal hydroxide, heating to complete saponication of said fatty acid,adding mineral oil and cooking and stirring to form said grease.

5. Process as in claim 4 wherein at least part of said furfuryl alcoholis esteriiied by adding excess fatty acid.

6. Process as in claim 4 wherein at least part gif said furfural alcoholis removed by evapora- 7. Process as in claim l wherein at least partoi' said alcohol is removed by evaporation.

8. Process as in claim 1 wherein at least part of said alcohol isesterified with an excess of said saponiable fatty material.

9. Process according to claim 4 wherein said metal hydroxide ls sodiumhydroxide.

10. Process as in claim 4 wherein said metal hydroxide is an alkalineearth metal hydroxide.

11. Process as in claim 4 wherein said metal hydroxide is lithiumhydroxide.

12. Process as in claim 4 wherein at least a portion of said furfurylalcohol is incorporated into said grease as a plasticizer.

13. A lubricating grease composition consisting essentially of alubricating oil thickened to a grease consistency with 5 to 50% byweight, based on the total composition, of a combination of 1 to 4 molarproportions of a soap of aliphatic carboxylic acid of 12 to 22 carbonatoms with 1 to 4 molar proportions of a salt of a cyclic carboxylicacid oi' lower molecular weight than said aliphatic acid, saidcomposition including also a minor amount of a fatty acid ester of analcohol corresponding to said cyclic acid.

14. A lubricating grease composition consisting essentially of alubricating oil thickened to a grease consistency with 5 to 50% byweight, based on the total composition, of a combination of 1 to 4 molarproportions of a soap of aliphatic carboxylic acid oi 12 to 22 carbonatoms combined with 1 to 4 molar proportions of a metal salt of furoicacid, said composition containing also a minor amount of a fatty acidester of furfuryl alcohol.

15. Composition as in claim 13 wherein said oil is mineral base oil.

16. Composition as in claim 13 wherein said oil is predominantly asynthetic oil.

17. Composition as in claim 13 wherein said anais? 13 alcohol estercomprises 0.01 to 5% of the total weight.

18. Composition as in claim 14 wherein said furfuryl alcohol estercomprises 0.01 to 5% of the total weight.

19. A lubricating grease composition consisting essentially oflubricating oil thickened to a grease consistency with about 5 to 25% byweight, based on the total composition, of metal soap of C12 to C22aliphatic carboxylic acid and about 3 to 15% of metal salt of aheterocyclic carboxylic acid of lower molecular weight than saidaliphatic acid, and 0.01 to 5% of the ester of said aliphatic acid andthe alcohol corresponding to said heterocyclic acid.

20. Composition as in claim 19 wherein said metal is sodium.

2l. A lubricating grease composition, consisting essentially of oil oflubricating grade thickcned to a grease consistency with 5 to 50% byweight, based on the total composition, of a combination of 1 to 4 molarproportions of a metal soap of fatty acids with 1 to 4 molar proportionsof the salt contained in the Cannizzaro reaction products of a cyclicaldehyde of molecular weight below that of C12 aliphatic carboxylic acidand a strong base.

22. The process of preparing a lubricating grease composition whichcomprises combining l'to 4 molar parts of an aldehyde of relatively lowmolecular weight and capable of undergoing the Cannizzaro reaction withsufficient proportions of strong base to substantially convert saidaldehyde to carboxylic acid salt and the corresponding alcohol, andcombining 1 to 4 molar parts of a saponilable fatty material ofrelatively high molecular weight having between about 12 and 22 carbonatoms with saponifying agent to form a. soap, and incorporating saidsalt and soap in grease-thickening proportions into lubricating oil.

ARNOLD J. MORWAY.

JOHN J KOLFENBACH.

REFERENCES CITED The following; references are of record in the file ofthis patent:

UNITED STATES PA'I'ENTS Number Name Date 1,700,056 James Jan. 22. 19292,108,643 Brunstrum et al. Feb. 15, 1938 2,113,754 Zimmer et al. Apr.12, 1938 2,182,137 Ricketts Dec. 5, i939 2,409,950 Meyer Oct. 22, 19452,441,720 Roehner et al May 18, 1948 2,449,312 Murray Sept. 14. 19482,455,982 Fraserv Dec. 7, 1948 OTHER REFERENCES Fieser and Fieser:lOrganic Chemistry, pages 217 and 549, published 1944 by D. C. Heath andCompany of Boston.

1. THE PROCESS OF PREPARING A LUBRICATING GREASE COMPOSITION FOR HIGHTEMPERATURE USE WHICH COMPRISES COMBINING A CYCLIC ALDEHYDE CAPABLE OFUNDERGOING THE CANNIZZARO REACTION WITH AN ALKALI TO CONVERT PART OFSAID AIDEHYDE TO A CYCLIC CARBOXYLIC ACID SALT AND PART TO THECORRESPONDING ALCOHOL, ADDING A SAPONIFIABLE FATTY MATERIAL AND AFURTHER QUANTITY OF ALKALI TO FORM A SOAP AND ADDING LUBRICATING OIL,SAID SALT AND SOAP BEING COMBINED IN PROPORTIONS OF 1 TO 4 MOLAR PARTSOF SAID SALT WITH 1 TO 4 MOLAR PARTS OF SAID SOAP, SAID COMBINED SALTAND SOAP SERVING TO THICKEN SAID LUBRICATING OIL TO A GREASECONSISTENCY.